New compounds: peptide derivatives of the antitumor agent N-phosphonoacetyl-L-aspartic acid

Peptides and proteins as drugs

Relatively small modifications of clinically useful endogenous compounds have been shown to have therapeutically beneficial effects on their pharmacodynamic and pharmacokinetic properties. These effects include increased potency and effect selectivity, and prolonged duration of action. In addition, these modifications have resulted in compounds that can be administered orally where only parenteral administration was previously possible. One type of modification resulting in distinctive properties is exemplified by the hybrid interferons produced by the recombination of segments of genes coding for different molecular species. Chemical modification has also resulted in many examples of analogs of natural peptides that are more potent, more selective and more stable than the endogenous compounds. Conjugation to peptide or protein carriers is a third method used to selectively modify the properties of an endogenous compound. The carriers that have been used include synthetic polypeptides, endogenous proteins, toxins and monoclonal antibodies. The effect that covalent attachment to a carrier has on the properties of a ligand is highly dependent upon the carrier, the ligand and the linkage between them.

Antibacterial activity of phosphono peptides based on 4-amino-4-phosphonobutyric acid

Phosphono dipeptides based on 4-amino-4-phosphonobutyric acid (phosphonic acid analogue of glutamic acid, GluP) were synthesized and evaluated for their antibacterial activity. Dipeptides containing N-terminal alanine, leucine, isoleucine, phenylalanine or lysine showed marked antibacterial activity against Escherichia coli, whilst those containing alanine, leucine, valine or proline were active against Serratia marcescens. AlaGluP and LeuGluP were nearly equipotent with the respective dipeptides based on 1-aminoethylphosphonic acid (phosphonic acid analogue of alanine). The structure-activity relationship, i.e. dependence of the activity of phosphono dipeptides on the nature of their N-terminal component, indicated that transport of the peptide through the bacterial cytoplasmic membrane constitutes a crucial step in its antibacterial activity.